In an injection molding machine, such as an electric motor driven injection molding machine which includes a numerical control apparatus, a display unit equipped with a display screen and a manual data input device is utilized for setting various molding conditions, monitoring operational conditions alarming for the possible occurrence of abnormal operational condition and so on. Thus, the display unit is an important part of the injection molding machine.
Known conventional display units for injection molding machines are broadly categorized into three types; a stand type characterized in that a display unit is fixedly mounted on the top of a stand vertically standing from a floor, a built-in type characterized in that a display unit is housed inside the injection molding machine, and a pendant type which is characterized in that a display unit is suspended from a swing arm.
The stand type display unit has a disadvantage in that it can be an obstacle to workers, since it is fixedly disposed on the periphery of the injection molding machine. The built-in type display unit, especially a large size CRT display unit, large in both the size and weight, requires not only a larger housing space but a significant amount of labor for installation and removal from the injection molding machine.
The pendant type display unit (for example, as disclosed in the Japanese Unexamined Patent Application JP, A-63-107534) is convenient in that the display unit can change its position between an operational position and a retracted position. However, due to the restriction of mechanical strength, the length of the swing arm supporting the display unit must be limited. Thus, the movable range of the display unit is correspondingly limited. This is a drawback to the operability of the display unit, since an operator is limited in changing the position of the display unit to an optimum point.
Moreover, the swing arm needs to be placed at a fairly high position in order to avoid interference between the display unit and the main body of the injection molding machine. Accordingly, a pole to support the swing arm is required to have a considerable length which requires the rigidity of the supporting pole to be increased and therefore increase the cost.
Moreover, the pendant type display unit is usually positioned higher than an operation board of the injection molding machine, so that the operator needs to turn or look upwardly to watch the display screen or manipulate the data input apparatus of the display unit. Where it is necessary to alternately repeat the monitoring or manipulation of the display screen and the operation of the operation board of the injection molding machine, the operator is required to look in up-and-down directions. Thus, the pendant type display unit is disadvantageous in that the operator is required to turn and look so frequently.